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Selenium automates browsers. That's it! What you do with that power is entirely up to you.
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package org.openqa.selenium.remote.service;
import static java.util.Collections.emptyMap;
import static java.util.concurrent.TimeUnit.SECONDS;
import static org.openqa.selenium.concurrent.ExecutorServices.shutdownGracefully;
import java.io.Closeable;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.time.Duration;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.ReentrantLock;
import java.util.logging.Logger;
import org.openqa.selenium.Beta;
import org.openqa.selenium.Capabilities;
import org.openqa.selenium.ImmutableCapabilities;
import org.openqa.selenium.WebDriverException;
import org.openqa.selenium.internal.Require;
import org.openqa.selenium.net.PortProber;
import org.openqa.selenium.net.UrlChecker;
import org.openqa.selenium.os.ExternalProcess;
/**
* Manages the life and death of a native executable driver server. It is expected that the driver
* server implements the WebDriver Wire Protocol.
* In particular, it should implement /status command that is used to check if the server is alive.
* In addition to this, it is supposed that the driver server implements /shutdown hook that is used
* to stop the server.
*/
public class DriverService implements Closeable {
public static final String LOG_NULL = "/dev/null";
public static final String LOG_STDERR = "/dev/stderr";
public static final String LOG_STDOUT = "/dev/stdout";
private static final String NAME = "Driver Service Executor";
protected static final Duration DEFAULT_TIMEOUT = Duration.ofSeconds(20);
private static final Logger LOG = Logger.getLogger(DriverService.class.getName());
private final ExecutorService executorService =
Executors.newFixedThreadPool(
2,
r -> {
Thread thread = new Thread(r);
thread.setName(NAME);
thread.setDaemon(true);
return thread;
});
/** The base URL for the managed server. */
private final URL url;
/** Controls access to {@link #process}. */
private String executable;
private final ReentrantLock lock = new ReentrantLock();
private final Duration timeout;
private final List args;
private final Map environment;
/**
* A reference to the current child process. Will be {@code null} whenever this service is not
* running. Protected by {@link #lock}.
*/
protected ExternalProcess process = null;
private OutputStream outputStream = System.err;
/**
* @param executable The driver executable.
* @param port Which port to start the driver server on.
* @param timeout Timeout waiting for driver server to start.
* @param args The arguments to the launched server.
* @param environment The environment for the launched server.
* @throws IOException If an I/O error occurs.
*/
protected DriverService(
File executable,
int port,
Duration timeout,
List args,
Map environment)
throws IOException {
if (executable != null) {
this.executable = executable.getCanonicalPath();
}
this.timeout = timeout;
this.args = args;
this.environment = environment;
this.url = getUrl(port);
}
public String getExecutable() {
return executable;
}
public void setExecutable(String executable) {
this.executable = executable;
}
protected List getArgs() {
return args;
}
protected Map getEnvironment() {
return environment;
}
protected URL getUrl(int port) throws IOException {
return new URL(String.format("http://localhost:%d", port));
}
protected Capabilities getDefaultDriverOptions() {
return new ImmutableCapabilities();
}
protected String getDriverName() {
return null;
}
public String getDriverProperty() {
return null;
}
protected File getDriverExecutable() {
return null;
}
/**
* @return The base URL for the managed driver server.
*/
public URL getUrl() {
return url;
}
/**
* Checks whether the driver child process is currently running.
*
* @return Whether the driver child process is still running.
*/
public boolean isRunning() {
lock.lock();
try {
return process != null && process.isAlive();
} catch (IllegalThreadStateException e) {
return true;
} finally {
lock.unlock();
}
}
/**
* Starts this service if it is not already running. This method will block until the server has
* been fully started and is ready to handle commands.
*
* @throws IOException If an error occurs while spawning the child process.
* @see #stop()
*/
public void start() throws IOException {
lock.lock();
try {
if (process != null) {
return;
}
if (this.executable == null) {
if (getDefaultDriverOptions().getBrowserName().isEmpty()) {
throw new WebDriverException("Driver executable is null and browser name is not set.");
}
this.executable = new DriverFinder(this, getDefaultDriverOptions()).getDriverPath();
}
LOG.fine(String.format("Starting driver at %s with %s", this.executable, this.args));
ExternalProcess.Builder builder =
ExternalProcess.builder().command(this.executable, args).copyOutputTo(getOutputStream());
environment.forEach(builder::environment);
process = builder.start();
CompletableFuture serverStarted =
CompletableFuture.supplyAsync(
() -> {
waitUntilAvailable();
return StartOrDie.SERVER_STARTED;
},
executorService);
CompletableFuture processFinished =
CompletableFuture.supplyAsync(
() -> {
try {
return process.waitFor(getTimeout())
? StartOrDie.PROCESS_DIED
: StartOrDie.PROCESS_IS_ACTIVE;
} catch (InterruptedException ex) {
return null;
}
},
executorService);
try {
StartOrDie status =
(StartOrDie)
CompletableFuture.anyOf(serverStarted, processFinished)
.get(getTimeout().toMillis() * 2, TimeUnit.MILLISECONDS);
if (status == null) {
throw new InterruptedException();
}
switch (status) {
case SERVER_STARTED:
processFinished.cancel(true);
break;
case PROCESS_DIED:
process = null;
throw new WebDriverException("Driver server process died prematurely.");
case PROCESS_IS_ACTIVE:
process.shutdown();
throw new WebDriverException("Timed out waiting for driver server to bind the port.");
}
} catch (ExecutionException e) {
process.shutdown();
throw new WebDriverException("Failed waiting for driver server to start.", e);
} catch (TimeoutException e) {
process.shutdown();
throw new WebDriverException("Timed out waiting for driver server to start.", e);
} catch (InterruptedException e) {
process.shutdown();
Thread.currentThread().interrupt();
throw new WebDriverException("Interrupted while waiting for driver server to start.", e);
}
} finally {
lock.unlock();
}
}
protected Duration getTimeout() {
return timeout;
}
protected void waitUntilAvailable() {
try {
URL status = new URL(url.toString() + "/status");
new UrlChecker().waitUntilAvailable(getTimeout().toMillis(), TimeUnit.MILLISECONDS, status);
} catch (MalformedURLException e) {
throw new WebDriverException("Driver server status URL is malformed.", e);
} catch (UrlChecker.TimeoutException e) {
throw new WebDriverException("Timed out waiting for driver server to start.", e);
}
}
/**
* Stops this service if it is currently running. This method will attempt to block until the
* server has been fully shutdown.
*
* @see #start()
*/
public void stop() {
lock.lock();
WebDriverException toThrow = null;
try {
if (process == null) {
return;
}
if (hasShutdownEndpoint()) {
try {
URL killUrl = new URL(url.toString() + "/shutdown");
new UrlChecker().waitUntilUnavailable(3, SECONDS, killUrl);
try {
process.waitFor(Duration.ofSeconds(10));
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
} catch (MalformedURLException e) {
toThrow = new WebDriverException(e);
} catch (UrlChecker.TimeoutException e) {
toThrow = new WebDriverException("Timed out waiting for driver server to shutdown.", e);
}
}
process.shutdown();
if (getOutputStream() instanceof FileOutputStream) {
try {
getOutputStream().close();
} catch (IOException ignore) {
}
}
} finally {
process = null;
lock.unlock();
close();
}
if (toThrow != null) {
throw toThrow;
}
}
protected boolean hasShutdownEndpoint() {
return true;
}
public void sendOutputTo(OutputStream outputStream) {
this.outputStream = Require.nonNull("Output stream", outputStream);
}
protected OutputStream getOutputStream() {
return outputStream;
}
@Override
public void close() {
shutdownGracefully(NAME, executorService);
}
private enum StartOrDie {
SERVER_STARTED,
PROCESS_IS_ACTIVE,
PROCESS_DIED
}
public abstract static class Builder> {
private int port = 0;
private File exe = null;
private Map environment = emptyMap();
private File logFile;
private Duration timeout;
private OutputStream logOutputStream;
/**
* Provides a measure of how strongly this {@link DriverService} supports the given {@code
* capabilities}. A score of 0 or less indicates that this {@link DriverService} does not
* support instances of {@link org.openqa.selenium.WebDriver} that require {@code capabilities}.
* Typically, the score is generated by summing the number of capabilities that the driver
* service directly supports that are unique to the driver service (that is, things like "{@code
* proxy}" don't tend to count to the score).
*/
public abstract int score(Capabilities capabilities);
/**
* Sets which driver executable the builder will use.
*
* @param file The executable to use.
* @return A self reference.
*/
@SuppressWarnings("unchecked")
public B usingDriverExecutable(File file) {
Require.nonNull("Driver executable file", file);
this.exe = file;
return (B) this;
}
/**
* Sets which port the driver server should be started on. A value of 0 indicates that any free
* port may be used.
*
* @param port The port to use; must be non-negative.
* @return A self reference.
*/
public B usingPort(int port) {
this.port = Require.nonNegative("Port number", port);
return (B) this;
}
protected int getPort() {
return port;
}
/**
* Configures the driver server to start on any available port.
*
* @return A self reference.
*/
public B usingAnyFreePort() {
this.port = 0;
return (B) this;
}
/**
* Defines the environment for the launched driver server. These settings will be inherited by
* every browser session launched by the server.
*
* @param environment A map of the environment variables to launch the server with.
* @return A self reference.
*/
@Beta
public B withEnvironment(Map environment) {
this.environment = Map.copyOf(environment);
return (B) this;
}
/**
* Configures the driver server to write log to the given file.
*
* @param logFile A file to write log to.
* @return A self reference.
*/
public B withLogFile(File logFile) {
this.logFile = logFile;
return (B) this;
}
public B withLogOutput(OutputStream output) {
this.logOutputStream = output;
return (B) this;
}
protected File getLogFile() {
return logFile;
}
/**
* Configures the timeout waiting for driver server to start.
*
* @return A self reference.
*/
public B withTimeout(Duration timeout) {
this.timeout = timeout;
return (B) this;
}
protected Duration getDefaultTimeout() {
return DEFAULT_TIMEOUT;
}
protected OutputStream getLogOutput() {
if (logOutputStream != null) {
return logOutputStream;
}
try {
File logFile = getLogFile();
return logFile == null ? OutputStream.nullOutputStream() : new FileOutputStream(logFile);
} catch (FileNotFoundException e) {
throw new RuntimeException(e);
}
}
protected void parseLogOutput(String logProperty) {
if (getLogFile() != null || logOutputStream != null) {
return;
}
String logLocation = System.getProperty(logProperty, LOG_NULL);
switch (logLocation) {
case LOG_STDOUT:
withLogOutput(System.out);
break;
case LOG_STDERR:
withLogOutput(System.err);
break;
case LOG_NULL:
withLogOutput(OutputStream.nullOutputStream());
break;
default:
withLogFile(new File(logLocation));
break;
}
}
/**
* Creates a new service to manage the driver server. Before creating a new service, the builder
* will find a port for the server to listen to.
*
* @return The new service object.
*/
public DS build() {
if (port == 0) {
port = PortProber.findFreePort();
}
if (timeout == null) {
timeout = getDefaultTimeout();
}
loadSystemProperties();
List args = createArgs();
DS service = createDriverService(exe, port, timeout, args, environment);
service.sendOutputTo(getLogOutput());
port = 0; // reset port to allow reusing this builder
return service;
}
protected abstract void loadSystemProperties();
protected abstract List createArgs();
protected abstract DS createDriverService(
File exe, int port, Duration timeout, List args, Map environment);
}
}